Abstract
In situ hybridization (ISH) is an ultra-sensitive technique for analyzing gene expression at the cellular level, enabling the detection of specific genes. It is an indispensable method, particularly in studies on developmental differentiation and morphogenesis, and is also attracting attention for its clinical application to biomarker detection. We focused on periostin (POSTN), an extracellular matrix protein, and examined the histological expression patterns of POSTN mRNA, particularly pathological splicing variants, in malignant tumors, such as breast cancer and tongue cancer, to investigate the potential of novel therapies targeting POSTN. However, POSTN mRNA staining has not yet been performed on the tissues of odontogenic tumors and cysts. Therefore, we herein examined the expression patterns of POSTN mRNA in human explants of dentigerous cysts, orthokeratinized odontogenic cysts, and odontogenic keratocysts, which are commonly encountered in clinical practice, using ISH. The results obtained suggest that POSTN mRNA was mainly expressed in fibroblasts in all odontogenic cysts, and the intensity of expression appeared to vary depending on the presence of inflammation. In odontogenic keratocysts after decompression, POSTN mRNA was highly expressed in the basal cell layer. ISH enabled the cellular localization of POSTN to be identified, which was difficult by immunohistochemistry, showing the potential of its clinical application to biomarker detection not only in odontogenic cysts, but also in all diseases of the oral and maxillofacial region. (J Osaka Dent Univ 2025; 59: 141-150)
